Radio receiving system



Feb. 10, 1925. 1,s2s,s'2s

J. WEINBERGER RADIO RECEIVING SYSTEM Filed March 5, 1921 Patented Feb. 10, 1925.

UNITED STATES PATENT OFFICE.

JULIUS WEINBERGER, OF NEW YORK, N. Y., ASSIGNOR TO RADIO CORPORATION OF AMERICA, A CORPORATION OF DELAWARE.

mm RECEIVING SYSTEM.

Application filed March a, 1921. Serial No. 449,468.

To all whom it'may concern:

Be it known that I, J ULIUs WEINBERGER, a citizen of the United States, residing in the borough of Manhattan, city, county, and State of New York, have invented certain new and useful Improvements in Radio Receiving Systems, of which the following is a specification. r

This invention relates to radio communication and aims to provide means for eliminating interference.

Since all electromagnetic waves reaching a receiving antenna produce an effect to a greater or less extent, it is necessary to adopt means for eliminating or reducing the effects of all waves but the ones proceeding from the desired sending station. Various means have been proposed for this purpose, the most common probably involving the tuning of the antennae and receiving circuits to the wave length to be received, This is more or less successful when the desired wave and the interfering Waves are of the same order of strength and of widely. difierent frequencies but it is of little use when the interfering waves are much stronger than the desired waves and of nearly the same fre quency. Interference of this nature is encountered when the receiving station is near to an interfering transmitting station as compared to its distance from the transmitting station being received.

The aim of my invention is to overcome relatively strong interference of this kind, though it may be used for the prevention of interference regardless of the strength of the interfering current. I

The invention can be applied in various ways but I have shown by way of example an embodiment in the single figure of the accompanying drawings.

The arrangement illustrated comprises an antenna 1 which may be aperiodic or resonant to the signal fre uency and including the usual primary coi 2 and tuning condenser 3. Two intermediate circuits 4 and 5 derive energy from the antenna; Circuit 4 is coupled to the antenna and tuned, for

' example, by means of a condenser 6, to the desired signal frequency whereby it has a relatively high ratio of signal current to interference current. Circuit 5 is made resonant to the interfering frequency. by means of a condenser 7, for example, where by a relatively high ratio of interference to signal is obtained therein. As shown in the drawing, a circuit 8, which is non-resonant, is coupled to circuits 4 and 5, in order to provide a means of varying the reaction of circuit 5 on circuit 4 and vice versa. I

Phase adjusting means .of suitable kind are utilized for obtaining desired phase re-,

lations between the currents in circuits 4 and I 5. The arrangement shown inthe drawing for this purpose is especially advantageous and simple, and comprises a phase shifter 10 consisting of inductance 11 in circuit 4, in parallel with inductance 12, capacity 13 and resistance 14. The divided circuit described is coupled to the rotatable coil 15, which is adjustable as to the coupling with thebranched circuits so that any desired phase relation maybe obtained between the currents-in the circuits 5 and 8 in relation to 'the current in circuit 4. The theory and operation of phase shifters is well understood and therefore the operation will not be further described. Circuits 4 and 5 are coupled to a receiving circuit 16 resonant to the signal frequency and the currents therein are amplified and detected in any well known manner. A valve circuit 17 is shown for this purpose, but as any other suitable arrangement can be used, the one shown will not be particularly described.

For eliminating interference, the strength or amplitude of the interfering voltages impressed on the receiving circuit 16 by circuits 4 and 5 is adjusted to substantial equality in any suitablemanner, for example, by varying the coupling between one or more of circuits 4, 8, 5 and 16, and the interfering currents in the receiving circuit are then brought into opposite phase relations by means of the phase shifter.

When these adjustments are made the relatively small amount of interference impressed on the receiver circuit 16 by the circuit 4 on account of its being resonant to the signal frequency, will be cancelled by an equal amount of interference derived from circuit 5. As the latter circuit is resonant to the interfering frequency and therefore has a high ratio of interference to signal, the adjustment will not balance out any considerable amount of the desired signal.

Having described my invention what I claim is:-

1. In a radio receiving system for eliminating interference, the combination of an antenna, a receiving circuit tuned to the sig 2. In a radio receiving system for elimi nating interference, the combination of an antenna, a receiving circuit tuned to the signal frequency, and two intermediate circuits coupled to the receiving circuit and deriving signal and interference currents from said antenna, one of said intermediate circuits having a relatively high ratio of signal'current to interfering currents and the other tuned to the interference and having a relatively high ratio of interfering currents to signal current, said intermediate circuits being associated with the receiving circuit so that equal interfering currents of opposite phase are induced therein.

3. In a radio receiving system for eliminating interference the combination of an antenna, a receiving circuit tuned to the signal frequency and two intermediate circuits coupled to the receiving circuit and deriving, the signal and interfering currents from said antenna, one of said intermediate circuits being tuned to the signal frequency and the other to the interfering frequency, saidintermediate circuits being associated so that the interfering currents oppose in the receiving circuit.

4. In a radio receiving system for eliminating interference, the combination of an antenna, a receiving circuit tuned to the.

signal fre uency and two intermediate circuits coup ed .to the receiving circuit and deriving signal and interference currents from said antenna, one of said intermediate circuits being tuned to the signal frequency and the other tuned to the interfering. frequency, said intermediate circuits being associated with the receiving circuit so that equal interfering currents of opposite phase are induced in the receiving circuit.

5. In a radio receiving system for elimi nating interference, the combination of an antenna, a receiving circuit tuned to the signal frequency, two intermediate circuits coupled to thereceiving circuit andderivsignal and interference currents from sald antenna, one of said intermediate circuits having a relatively high ratio of signal current to interfering currents and the other tuned to the interference and having a relatively high ratio of interfering cur rents to signal current, and means for ad currents in the second intermediate circu t neaaaae justing the interfering currents impressed on the receiving circuit into opposition.

6. In a radio receiving'system for eliminating interference, the combination of an antenna, a receiving circuit tuned to the signal frequency, two intermediate circuits coupled to the receiving circuit and deriving signal and interference currents from said antenna one of said intermediate circuits having a relatively high ratio of signal current to interfering current and the other tuned to the interference and having a relatively high ratio of interfering current to signal current, and means for adjusting the interfering currents. induced in the receiving circuit into opposite'phase relations.

7. In a radio receiving system for eliminating interference the combination of an antenna, a receiving circuit tuned to the signal frequency, two intermediate circuits coupled to the receiving circuit and deriving signal and interference currents from said antenna, one of said intermediate circuits having a relatively high ratio of signal current to interfering current and the other ltuned to the interference and having a relatively .high ratio of interfering current to signal current, and means for adjusting the interference currents to the same value and into opposite phase relations as to their effects on the receiving circuit.

. 8. In a radio receiving system for eliminating interference the combination of an antenna, a receiving circuit tuned to the signal frequency, 'an intermediate circuit tuned to the signal frequency coupled to the antenna and receiving circuits, a second intermediate circuit tuned to the interfering frequency and coupled to the first mentioned intermediate circuit and to the re ceiving circuit, and means for adjusting the interfering currents impressed on the receiving circuit into opposition.

9. In a radio receiving system for eliminating interference, the combination of an antenna, a receiving circuit tuned to the signal frequency, an intermediate circuit coupled to the antenna and receiving circuit and tuned to the signal frequency, a second intermediate circuit coupled to the first intermediate circuit and to the receiving circuit and tuned to the interfering frequency, and means for adjusting the phase of the so that interfering currents oppose in e receiving circuit.

10. In a radio receiving system for eliminating interference, the combination of an antenna, a receiving circuit tuned to the signal frequency, an intermediate circuit coupled to the antenna and the receiving circuit and tuned to the signal frequency, a second intermediate circuit tuned to the interfering frequency and coupled to the first intermediate circuit and receiving circuit and means for adjusting the irierfei'ing currents to the same value and opposite phase relation inthe receiving circuit.

11. In a radio receiving system for eliminating interference, the combination of an antenna, a receiving circuit tuned to the signal frequency, an intermediate circuit coupled to the antenna and receiving cir-J cuit and tuned to the signal frequency, a

second intermediate circuit, a phase shifter 10 having one member associated with the first and another member associated with the second intermediate circuit, and a third intermediate circuit tuned tothe interfering frequency and coupled to the second interi5 mediate'circuit and to the receiving circuit.

JULIUS WEINBERGER. 

